I am not a fan of Harry Potter (though I am a fan of Lord of the Rings); but from what I heard of the series, it sounds like she lifted more than a few concepts, components, etc. from Tolkien.
It’s amazing that nearly sixty years after Tolkien wrote Lord of the Rings, writers are still (to some degree or another) imitating him. Amazing what a fellow who would otherwise have been an obscure philologist and professor accomplished.
She uses Jane Austin a lot. It’s called narrative misdirection. We see everything from Harry’s point of view and so miss out on a lot of information. We think as he thinks and end up getting misdirected in every book until at the end, “I open at the close.” If you only watch the movies and you treat the books as children’s books, they are successful but basically boring to adults. If you approach them as literature, they are very successful. Of course, literature is not everyone’s cup of tea. Harry Potter has brought me back to Shakespeare, Jane Austin, and Dante. The Hero’s Journey is only one of the more shallow approaches to take. The theological approach is fascinating too. In every book he goes beneath the ground and rises in the presence or because of a symbol of Christ. In the last book Harry is the symbol.
Not to mention C.S. Lewis' "Prince Caspian" in which he has Peter, Edmund, Susan and Lucy transported to their alternate world (Narnia) via a train leaving an underground station.
All art is derivative, if you copy and publish from a single source, it's plagiarism, if from multiple sources, it's "research".
Regards,
GtG